The Meaning of Life, the Universe, and Everything.
Sometimes I find there's an Ender Crystal left after I kill the dragon. What if they could make it that Ender Crystals can be harvested (through a time consuming process so you don't use it as a means of taking them away from the dragon). They would then be useful in crafting powerful items. I'm thinking 1 can be broken up into four Ender Crystal fragments, three of which makes a kind of pick that can cut Bedrock. 3 full ender crystals lets you make a pick that can actually harvest bedrock. 3 ender crystals would be an unheard of thing to get since it would require defeating a regenerating dragon. A real challenge. But then there would be a use for Bedrock, perhaps the only way to craft an additional kind of portal into another world.
A single ender crystal fragment could be made into an incredibly powerful light source, or perhaps thrown into the void, where it converts the bottom layer of a world into lava for an entire chunk where it hits that lowest level.
I'm thinking you could harvest them by simply putting lava on them. Every second it runs there's a small chance the crystal will separate from the bedrock it's sitting on and float away on the lava much like other items float away on water.